Faculty who do research in hearing science and its applications came together from several schools and colleges in 1995 to form the Hearing Research Center (HRC) at B.U. for "the development and dissemination of knowledge that will improve the nation's auditory health and allow the fullest utilization of the sense of hearing." Since the year 2000, a P30 Core Center grant has supported two cores, a Sound-Field Laboratory Core and an Engineering Support Core. This application requests the renewal of this grant which provides critical assistance for sharing facilities, support personnel, equipment, and expertise;for the development of mechanisms for sharing data and models across laboratories;and for the promotion of scientific interactions among faculty in different laboratories at BU and at other institutions in the area. The requested core support is designed to promote integrative, multidisciplinary collaborations involving auditory physiology, psychoacoustics, and computational modeling. Support for two Core facilities is requested: the Sound Field Laboratory facility and an Engineering Core facility. The Sound-Field facility provides a controlled, adjustably reverberant environment, allows common setups and stimuli in acoustic and psychoacoustic measurements, and provides support for acoustic and psychoacoustic measurements. The Engineering Core facility allows the archiving and analysis of data from groups working in different disciplines, the integration of modeling efforts that are distributed across different laboratories and at different levels of the auditory pathway, and provide general computer and technical support to all faculty and laboratories in the Core Center. These Cores and the support they provide are designed specifically to use resources efficiently, to promote collaboration, and to develop resources of general use to the hearing research community. The work supported by this Core Center extends our experiments to environments that are acoustically more complex yet still controlled and extends our capability to use more complex data sets and more complex models of physiology and perception. These areas are critical for the understanding of hearing in complex environments, an area of great difficulty for listeners with hearing impairments or cochlear implants.